With the advent of modern experimental techniques the low dimensional structures having quantum confinement in one, two and three dimensions such as (quantum well (QWs), quantum well wires (QWWs) and quantum dots (QDs) ultrathin films have in the last few years attached much attention not only because of their potential in uncovering new phenomena in computational and theoretical nanoscience but also for new technological applications. In ultrathin films, the restriction of the motion of the carriers in the direction normal to the films leads to the quantum size effect allowing two-dimensional carrier transport parallel to the surface of the film. In this context I shall study the DMR in ultrathin films of IIIV semiconductors.
I study the dimension-dependent (such as quantum well (QWs), quantum well wires (QWWs) and quantum dots (QDs)) transport in different nano-structures and the derivation of the expressions of many important transport coefficients are based on the temperature dependent electron concentration in nonlinear optical and optoelectronic nanostructure materials. The results for the corresponding emission and the electron statistics in the constituent materials have also been obtained. The thickness and the doping dependences of the field emission from all the aforementioned cases have been studied for the purpose of relative comparison, taking GaxAsyP1-y and AlAs lattice matched to InP quantum wire superlattice (QWSL) as an example.
An attempt is made to study the energy spectrum of the transmission electrons and analogous density-of-states function of degenerate semiconductors in the occurrence of an electric field strength. It is found, captivating n-GaAs as an example that the isotropic parabolic energy spectrum converts into an anisotropic dispersion relation with energy dependent mass anisotropy in the occurrence of electric field strength. In addition the band gap increases with electric field strength and the carriers vanish from the transmission band edge after definite value of the electric field strength. The eminent consequence of the density-of-states function for non-degenerate wide gap optical and optoelectronic materials with parabolic
energy band has been obtained as special cases of our generalized theory under definite limiting background from our generalized term when electric field strength is zero.
I study the magnetic susceptibilities in quantum wires of II-VI and IV-VI materials under a parallel magnetic field
on the basis of a newly formulated electron dispersion law. It has been found taking quantum wires of nano
compounds as an example that the mass and molar susceptibilities increase with decreasing film thickness and
decreasing electron concentration respectively within the limit of quantum framework. I observe that the
susceptibility ratio in both the cassese deviates from the well known 1/3 rd rule collectively with the fact that there is
a critical zone within which the quenching of diamagnetic mass and molar susceptibility occurs.
An attempt is made to study the Einstein relation for the diffusivity-mobility ratio (DMR) in nonlinear optical and
Optoelectronic compounds on the basis of a newly formulated electron energy spectrum. The results for ternary, III-V and quaternary
types of optoelectronic materials form a special case of our generalized investigation. I have also studied the DMR in II-VI, Bi, IV-VI and stressed materials on the basis of various band models as applicable for such focused materials. It has been found taking n-Cd3As2, n-CdGeAs2, n-InAs, n-InSb, n-Hg1-xCdxTe, n-In1-xGaxAsyP1-y lattice matched to InP, CdS, Bi, PbS, PbTe, PbSe and stressed InSb as
examples of the aforementioned compounds that the DMR increases with increasing electron concentration in various manners for
different band constants of the said materials and the rates of variation are totally band structure dependent. Now the well-known
results for non-degenerate wide gap optical and Optoelectronic materials have been obtained as special cases of our generalized theory under definite limiting background.
An attempt is made to study the carrier contribution to the elastic constants in QWs and QWWs of II-V , IV-VI, III-V, ternary
and quaternary types of optoelectronic compounds. It has been found, taking QWs and QWWs of CdGeAs2, InAs, Hg1-xCdxTe,
In1-xGaxAsyP1-y lattice matched to InP, CdS and PbSe as examples for numerical computations that the second and third order
elastic constants increase with increasing carrier degeneracy and decreasing film thickness respectively in various oscillatory
manners emphasizing the influence of dimensional quantizations and the energy band constants in different cases. An
experimental method of determining the said contribution in QWs and QWWs having arbitrary dispersion laws has also been
suggested and the present simplified analysis is in agreement with the suggested relationship. The well-known results for widegap
materials having nondegenerate electron concentration have also been obtained as special cases of our generalized theory
under certain limiting conditions.
I have study in this paper to present a simple theoretical analysis of the thermo electric
power under strong magnetic quantization (TPM) in superlattices with graded interfaces and
compare the same with that of the constituent materials by formulating the respective dispersion
laws. It has been observed, taking GaAs/Ga1-xAlxAs, CdS/CdTe, PbTe/PbSnTe, InAs/GaSb and
HgTe/CdTe with graded interfaces as examples, that the TPM exhibits oscillatory dependence
with the inverse quantizing magnetic field due to the SdH and allied superlattices effects and
increases with increasing inverse electron concentration in an oscillatory manner in all the cases.
The nature of oscillation is totally band structure dependent and the width of the finite interface
enhances the numerical values of the TPM for all the aforementioned superlattices. The
numerical values of the TPM in graded superlattices are greater than that of the constituent
materials. In addition, the well-known expressions for the bulk specimens of wide-gap materials
have also been obtained as special cases of our generalized analysis under certain limiting
conditions.
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